Research On Arthropod Community In Tall Fescue Artificial Grassland

In this study, we adopted methods of path analysis, principal component analysis, clustering analysis, and optimal partition systematically to studied the structural characteristics of arthropod community, explored spatial distribution dynamics of mixed spider population and analyze effect of cuttingon the structure and dynamics of arthropod community, on the basis of data from the comprehensive investigation on arthropod community in artificial tall fescue grassland. The results are as follows:1. According to relationship between nutrition and feeding from the species of arthropod community, We made a comprehensive investigation on the arthropod community of Tall fescue. The total community will be divided into natural enemy sub-community and non-natural enemy sub-community (including pests and neutral insect), According to investigated arthropod species, number of individual and various ecological indexes, we analysed structure from total community and sub-communities. The results showed that we totally investigated of 138 kinds Richards, they are part of 68 genera; non-natural enemy sub-communities were the major components of the total community, the relative abundance was 0.7661, in which Homoptera insects were the dominant species; the relative abundance of natural enemy sub-communities was 0.2339; the dominant species were spider type of natural enemy. Analysis about dominant concentration and dominance showed the following orders: non-natural enemy sub-community> total community> natural enemy sub-communities; diversity analysis showed the following orders : total community> natural enemy sub-community> non-natural enemy sub-communities2. The structure characterization of arthropod community and every sub-community in artificial tall fescue grassland changes regularly. The number of species and individual, dominant concentration, diversity index H', evenness, dominance and species richness of non-natural enemy sub-communities changes over time in line with the total community. The number of individuals of total arthropod community and non-natural enemy sub-communities showed bimodal changes, but the number of natural enemies lag. The species number of total community and non-natural enemy sub-communities reach the peak in late July to early August, but the number of species of natural enemy sub-communities reach peak value of 30 in mid-July and August, dominant concentration of the total arthropod community is mainly affected by non-natural enemy sub-communities; Diversity index H' of the total arthropod community and its sub-community showed trends of the low - high -low - high - low changes, rich gradually with kinds in the early period, diversity H' increased through to September, after September, diversity H' index decreased gradually, change range of diversity index H' of natural enemy sub-communities is smaller; The homogeneity of the total arthropod community and non-natural enemy sub-communities reach a higher level after mid-June, in addition to September, the homogeneity of natural enemy sub-communities was higher than non-natural enemy sub-communities; Dominance of total community and non-natural enemy sub-communities was higher from mid-April to early June, natural enemy dominance sub-communities was lower than the total community and non-natural enemy sub-communities from mid-April to early June, the highest in the September. Number of species and richness show small fluctuations in natural enemy sub-communities, with low - high - low trend in total community and non-natural enemy sub-communities, species richness of non-natural enemy sub-community and natural enemy sub-community changed in turn.3. We adopted method of path analysis to analyze relationship between diversity and other ecological indexes of total community and sub-communities. The results showed that diversity index H 'of total community were closely related to species richness (R), pielou evenness (E) and number of species (S), dominant concentration (C) and dominance (d) of the community increased while diversity of communities decreased, the species richness have the largest direct effect on the diversity of the community, diversity index H' of non-natural enemy sub-community were closely related to the species richness (R) and number of species (S), the effect of dominant concentration and dominance on the diversity of communities was got primarily through the number of species and richness,similar with the total community as well. non-natural enemy sub-community determined structure of arthropod community; number of species in natural enemy sub-communities played a decisive role on diversity. Adopted method of fuzzy clustering analysis, when the cluster distance D = 0.96, the total arthropod community and non-natural enemy sub-communities can be clustered into 3 categories, when D = 0.965, the natural enemy sub-communities can be clustered into 4 categories. The results of optimal partition show that total community, non-natural enemy sub-communities can be divided into 5 stages, three stages of non-natural enemy sub-community are slightly different from total community, their first and five stages are same; different periods of natural enemy sub-communities can be divided into 4 stages. The results showed that differences existed among species, number of species and dominant species in very stages. We adopted the method of principal component analysis to study the characteristic parameters of total arthropod community and its sub-community in 1 tall fescue artificial grassland. the contribution rate of summary indicator from first principal components in eigenvector matrix were 78.37%, 74.56% and 78.00% in non-natural enemy sub-communities, natural enemy sub-community respectively, the contribution rate of summary indicator from second principal components were 8.33%, 20.57% and 16.21%, the cumulative contribution rate of former two principal components were more than 94%, they illustrated the good effect of dimensionality reduction.4. In order to understand spatial distribution and timing sequence dynamic of spiders in artificial grassland, we made a comprehensive study on observational data by adopting systematic investigation of pitfall traps, five indexes degree of aggregation, power law principle of Taylor, comprehensive analysis of regression relation M~*-(x|-) of Iwao. The result was showed that the most of spiders collected by pitfall traps were wandering spiders, spatial distribution of spider population in artificial grassland of tall fescue showed a pattern of alternation in terms of timing sequence, the most of distributions were in collective state. 5. We adopted indexes of number of species (S), individual number (N), diversity index(H'), evenness index as the integrated indicator of diversity to analyzed the effect of different on structure and dynamics of arthropod community in tall artificial fescue grassland. The results showed that impact of cutting number was bigger on rare species, and less the dominant species common species; With the increase in the number of cutting, the number of arthropods decreased in non-natural enemy sub-communities, Impact of Cutting on the type and quantity of natural enemies was relatively small, the obvious differences of diversity and evenness indexes exhibited between arthropod community and its sub-community in the time course of changes, and was affected greater by the number of cutting, because the cutting cultivation decreased the number of pest population, and enhanced the diversity and evenness of community and natural control of natural enemies.